Fire out at Gulf oil rig, four hurt

An explosion and fire have ripped through a Gulf oil platform as workers used a cutting torch, sending four people to a hospital with burns and leaving two missing in waters off Louisiana.

Coast Guard Capt Ed Cubanski told a news conference in New Orleans on Friday the well was not producing at the time and no oil was leaking.

A small amount of oil spilled from the rig when workers using a torch cut into a 22-metre-long, 76-millimetre-wide line on the platform. Cubanski said a sheen 800-metres long and 200 metres wide was reported in the area.

"It's not going to be an uncontrolled discharge from everything we're getting right now," Cubanski said.

The fire had since been extinguished, said Coast Guard spokesman Drake Fore. He said Coast Guard aircraft and boats were searching for two missing people. Nobody was believed killed in the fire.

The platform is for oil production from an established well, unlike the Deepwater Horizon rig, which was drilling an exploratory well for oil giant BP in mile-deep water when it blew up and triggered a massive oil spill in 2010. That site is well to the east of Friday's explosion.

Taslin Alfonzo, spokeswoman for West Jefferson Medical Centre in suburban New Orleans, said four injured workers were brought to the hospital in critical condition with second- and third-degree burns over much of their bodies. Three arrived by helicopter at 9.55am local time and one by helicopter at 10.10am.

Two were sent by ambulance to the Baton Rouge Burn Centre. Two others were to be sent later.

The production platform owned by Black Elk Energy is about 40km southeast of Grand Isle, Louisiana. The Coast Guard said 26 people were aboard the platform at the time of the explosion.

Cubanski said the platform appeared to be structurally sound. After the April 2010 explosion on the Deepwater Horizon, that rig burned for about 36 hours before suffering structural collapse and sinking to the Gulf floor.